Should a patient with acute stroke be started immediately on aspirin (acetylsalicylic acid)?

From the Guidelines

Aspirin should be started as soon as possible after an ischemic stroke is confirmed, typically within 24 hours, with a loading dose of at least 160 mg, as this has been shown to reduce mortality and disability by preventing early recurrent strokes 1. The decision to start aspirin should be made after ruling out hemorrhagic stroke with brain imaging, as aspirin could worsen bleeding.

• The initial dose of aspirin can range from 160 to 300 mg, with a daily maintenance dose of 81-100 mg.
• Patients who are candidates for or have received thrombolytic therapy (like tPA) should not receive aspirin until 24 hours after the thrombolytic administration, as indicated by the guidelines from the American Heart Association/American Stroke Association 1.
• Aspirin works by inhibiting platelet aggregation, which helps prevent further clot formation and reduces the risk of recurrent stroke.
• The early administration of aspirin after ischemic stroke has been shown to reduce mortality and disability by preventing early recurrent strokes, with high-quality evidence from the Cochrane systematic review of four trials assessing the effect of early aspirin administration in patients with acute stroke 1.
• Patients should be advised that aspirin should be taken with food to minimize gastrointestinal side effects, and they should be monitored for any signs of bleeding.
• Long-term aspirin therapy is typically continued indefinitely unless contraindicated or replaced by another antithrombotic medication. Key considerations for starting aspirin in acute stroke patients include:
• Excluding hemorrhagic stroke with brain imaging
• Delaying aspirin administration in patients receiving thrombolytic therapy
• Monitoring for signs of bleeding
• Continuing long-term aspirin therapy unless contraindicated. The most recent and highest quality study, the 2018 Canadian Stroke Best Practice Recommendations, supports the use of aspirin in acute ischemic stroke, with a strong recommendation for its use in patients not already on an antiplatelet agent and not receiving alteplase therapy 1.

From the Research

Aspirin Therapy in Acute Stroke

• Aspirin has been shown to have a positive risk-benefit balance in patients with acute ischemic stroke, preventing about 5 deaths per 1000 patients 2.
• The benefits of aspirin in acute ischemic stroke include a reduction in the risk of recurrence and pulmonary embolism, although it carries a risk of hemorrhagic transformation 2.
• Aspirin should be given as soon as computed tomography has ruled out intracerebral haemorrhage, unless thrombolytic treatment is planned 2.

Timing of Aspirin Administration

• Antiplatelet therapy with aspirin, started within 48 hours of an acute ischemic stroke, is safe and effective, avoiding about 10 deaths and early recurrent strokes per 1,000 patients treated 3.
• Early aspirin use in acute ischemic stroke reduces the immediate risk of further stroke or death in hospital and the overall risk of death or dependency 4.
• Aspirin can be administered by mouth if the patient can swallow safely, or per rectum as a suppository if not 3.

Patient Selection for Aspirin Therapy

• Aspirin is beneficial for a wide range of patients with acute ischemic stroke, and its prompt use should be routinely considered for all patients with suspected acute ischemic stroke 4.
• The absolute reduction of approximately 7 per 1000 in recurrent ischemic stroke does not differ substantially with respect to age, sex, level of consciousness, atrial fibrillation, CT findings, blood pressure, stroke subtype, or concomitant heparin use 4.
• Even among patients randomized without a prior CT scan, aspirin appeared to be of net benefit with no unusual excess of hemorrhagic stroke 4.

Comparison with Dual Antiplatelet Therapy

• Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor has been shown to reduce the risk of recurrent stroke compared to aspirin alone, but at the expense of a higher risk of major bleeding events 5.
• The net benefit of DAPT initiated within 72 hours of symptom onset was pronounced in the first week and continued to a lesser degree in the following 2 weeks, outweighing the low but ongoing hemorrhagic risk 6.